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15. Stormwater: Existing water capacity should be expanded and improved in all ponding areas. The existing pond will be improved for water quality, storage and aesthetics. A walking path around the pond, or areas public enj oyment of the water should be a part of the reconstruction if financially feasible. Any redevelopment in the study area will require some types of water retention system. Innovative on-site management of storm water through rain gardens, storage in and under parking lots as well as providing on-site ponding that is an amenity to the development will be encouraged. (Refer to Appendix C for Estimated Impervious Surface Map) The Capital Region Watershed District (CRWD) reviewed the concept plans prepared as part of this Master Plan Study. A summary is presented below. Assum tin ons: • A 25-foot setback from the wetland. Wetland delineation should be completed prior to final approval of development plans. • The vacant parcel on Elmer Street is being considered for development and included in their analysis. (Conversations with theproperty owner indicated that there is noplan to develop the site in the nearfuture). • Total development based upon 40 new units. � Guptil site will be developed on both the north and south sides. • Impervious surface of 15,000 sq.ft. on the south side of Guptil and 10,000 sq,ft. on the north side of the site. (This impervious surface may change based upon a sharedparking arrangement with the Church). Conclusions• • StormwaterMana e� ment: A wet-bottom detention basin should be located to the west side of the Guptil parcel on the Armory site. (This has not been approved by theArmory but has beenproposed). The detention pond would be connected to the existing pond on the Armory site via a drainage way or swale located along the north property line. The south portion of the Guptil site should need to be regarded to direct the runoff into the proposed basins. Based upon some preliminary modeling, it is expected that this new pond or basin can meet the CRWD's requirement that the existing peak discharge rates for the 2, 5, 10 and 100 year storm events. However, as part of the development proposal, verification and remodeling must be completed to better determine proposed discharge rates. Water ualit : Initial modeling indicated that approximately 63.5% in annual total phosphorus reduction will be achievedthrough the assumed pond configuration. Based upon these assumptions, the pond is sized appropriately in order to meet CRWD's Final Version 14 July 26, 2004